First of all, if you feel that your mare isn't in good shape, contact your vets, he will give you good diagnosis in case of serious problem.
If you think it is just passenger, you can give for example :
- Haemolytan 400, it helps provide the elements necessary for red blood cell synthesis as well as for recovery after periods of intensive effort (foaling, gestation...)
- Mega Base Fertility, it helps to balance their diet during the lactation periods. The pelleted mineral complementary feeding stuff is rich in vitamins, amino acids to reply to the increased demands resulting from lactation.